JP2004069564A - Adhesion structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesion structure improving reliability of a sensor. <P>SOLUTION: In this adhesion structure for airtightly bonding a sensor case 3 holding a sensor element 5 inside with a housing 13, an annular recess part 17 is formed in one of the sensor case 3 and the housing 13, while an annular projection part 18 to be stored in the recess part 17 is formed in the other. When the projection part 18 is stored in the recess part 17, predetermined clearances 19 are arranged respectively between the inner circumference side faces and the outer circumference side faces of the projection part 18 and the recess part 17, and at least one of the clearances 19 is filled with an adhesive 20 to be bonded. In this process, a predetermined shape projection part 21 is arranged on at least one face among the side faces of the projection part 18 and the recess part 17 constituting the clearance 19 filled with the adhesive 20. Therefore, adhesion strength is increased as a whole and airtight adhesion between the sensor case 3 and the housing 13 can be achieved, and consequently, reliability as a sensor device can be improved. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a bonding structure for hermetically bonding a sensor case holding a sensor element therein and a housing.
[0002]
[Prior art]
Conventionally, as a sensor device having an adhesive structure in which an annular concave portion formed in a sensor case holding a sensor element therein and a convex portion formed in an annular shape in a housing via an adhesive, for example, a fluid There is a pressure sensor device for measuring pressure.
[0003]
This pressure sensor device holds a pressure sensor element in a sensor case, and the pressure sensor element is electrically connected to a lead frame for transmitting a signal to the outside (for example, an ECU) by a wire such as a gold wire. . Therefore, the material used for the sensor case needs to have heat resistance during wire bonding, and for example, polyphenylene sulfide (hereinafter, referred to as PPS) is used. Then, the concave portion formed in the sensor case and the convex portion formed in the housing made of, for example, polybutylene terephthalate (hereinafter, referred to as PBT) are adhered via an adhesive made of epoxy resin.
[0004]
[Problems to be solved by the invention]
However, when the sensor case and the housing are bonded as described above, the sensor case, the adhesive, and the linear expansion coefficient of each resin used for the housing at an actual use environment temperature may cause a difference between the sensor case and the housing. Peeling or the like occurs between the adhesive and the housing and between the adhesive and the housing. Therefore, there is a problem in that the pressure around the sensor element becomes unstable due to the leak path at the bonding portion, and the reliability as the pressure sensor decreases.
[0005]
The present invention has been made in view of the above problems, and has as its object to provide an adhesive structure with improved reliability of a sensor.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the bonding structure according to claim 1 is a bonding structure for hermetically bonding a sensor case and a housing that hold a sensor element therein, and one of the sensor case and the housing. And an annular concave portion, and the other has an annular convex portion in which the concave portion is housed. When the convex portion is stored in the concave portion, a predetermined gap is provided between the inner peripheral side surface and the outer peripheral side surface of the convex portion and the concave portion, and is bonded to at least one of the gaps between the inner and outer peripheral side surfaces. At this time, at least one of the side surfaces of the convex portion and the concave portion forming the gap filled with the adhesive is provided with a protrusion having a predetermined shape.
[0007]
As described above, when the predetermined protrusion shape is provided on at least one of the side surfaces of the convex portion and the concave portion facing the gap filled with the adhesive, the bonding area of the bonding surface in contact with the adhesive increases. As a result, the adhesive force between the adhesive and the sensor case or the housing increases. Also, in addition to the adhesive force in the pulling direction between the adhesive and the adhesive surface of the protrusion, an adhesive force in the shear direction is also generated, so that the adhesive strength is increased as a whole, and the airtight bonding between the sensor case and the housing can be achieved. Therefore, the reliability as a sensor device is also improved.
[0008]
As described in claim 2, it is preferable that the protrusion is formed on at least one side surface of the protrusion and the recess in one of the inner and outer gaps. If either the inner peripheral side or the outer peripheral side is firmly adhered to the adhesive, there is no possibility of forming a leak path. In addition, if projections are formed on both sides of the inner and outer peripheries and are firmly bonded to the adhesive, when a stress such as heat is applied, there is no place for the stress to escape. Therefore, it is sufficient that the protrusion is formed on at least one side surface of the protrusion and the recess that constitute one of the inner and outer gaps.
[0009]
As described in claim 3, the protrusions are provided on both inner peripheral side surfaces of the convex portion and the concave portion which are arranged to face each other, and both side surfaces of the convex portion and the concave portion forming the outer peripheral surface are formed flat. As described in claim 4, it is provided that both the outer peripheral side surfaces of the protruding portion and the concave portion arranged opposite to each other are formed, and both side surfaces of the convex portion and the concave portion forming the inner peripheral surface are formed flat. preferable. The present inventors investigated the adhesive strength when an adhesive was filled in the gap formed between the inner and outer peripheral side surfaces of the projection and the inner and outer peripheral side surfaces of the concave portion by a thermal cycle durability test. As a result, if the protrusions are not formed, peeling occurs between the outer peripheral side surface of the concave portion that is the outermost peripheral surface and the adhesive, and then peeling occurs between the inner peripheral side surface of both the convex portion and the concave portion and the adhesive. It became a leak path. Therefore, when there is no projection, the outer peripheral side surfaces including the outer peripheral side surface of the concave portion where the peeling has occurred first are flat without forming the protruding portion, and the protruding portions are formed on both the inner peripheral side surfaces of the convex portion and the concave portion. At this time, the projections on the inner peripheral side and the adhesive are firmly adhered to each other, and the stress caused by firmly adhering the inner peripheral side to the outer peripheral side can be relaxed. It is possible to more airtightly bond with the housing. Further, if a projection is formed on one side surface of the inner and outer circumferences and the other side surface is flat, the sensor case and the housing can be more airtightly bonded, so that the outer circumference side surface is formed. Protrusions may be formed on both side surfaces of the convex portion and the concave portion, and both side surfaces of the convex portion and the concave portion forming the inner peripheral side surface may be flat.
[0010]
As described in claim 5, it is preferable that the projections are a plurality of gathers that are parallel to the direction in which the projections are stored in the recesses and that project in a streak shape with a predetermined height and width. When a plurality of gathers are provided as the projections in this manner, the adhesive force acting in the shear direction acting between the adhesive and the adhesive surface further increases with the increase in the surface area of the gathers and the increase in the adhesive area to the adhesive. It will be. Therefore, the connection reliability between the adhesive and the sensor case or the housing is further improved. Further, when the gathers as the projections are integrally molded with the sensor case or the housing, the gathers are formed in parallel with the housing direction of the projections in the recesses, so that the sensor case or the housing including the projections can be formed from the resin mold. Can be easily extracted.
[0011]
As described in claim 6, it is preferable that the protrusions are provided uniformly on the entire periphery of the side surface of the protrusion and / or the recess. In particular, when the protrusion is formed only on one of the inner and outer circumferences, in order to maintain the airtightness between the sensor case and the housing, the bonding is performed depending on the presence or absence of the protrusion on the side surface on which the protrusion is formed. It is preferable not to provide a difference in adhesive strength between the agent and the agent.
[0012]
Further, as described in claim 7, the housing has a pressure introducing hole, and the sensor element detects the pressure introduced from the pressure introducing hole. Therefore, the adhesive structure according to the first to sixth aspects can be applied to the pressure sensor according to the seventh aspect.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First Embodiment)
FIG. 1 is an external cross-sectional view of a pressure sensor device, which is a sensor device in which a sensor case holding a sensor element therein and a housing are bonded, as an example of the bonding structure according to the embodiment of the present invention.
[0014]
The pressure sensor device 1 holds a mold IC 2 as an element for detecting pressure inside a sensor case 3.
[0015]
A concave fixing portion 4 is formed in the mold IC 2, and a sensor element 5 for detecting pressure is stored and fixed in the fixing portion 4. The molded IC 2 is formed by protecting a signal processing IC 6 for amplifying a signal of the sensor element 5 and a lead frame 7 for extracting the signal so as to be wrapped with a molded resin 8 such as an epoxy resin. .
[0016]
Here, the sensor element 5 is arranged so that a pressure-receiving surface that receives pressure is located at the opening of the fixing portion 4. The sensor element 5 and the lead frame 7 are formed by a wire using a wire 9 such as gold. They are electrically connected by bonding. The sensor element 5 has a configuration in which a plurality of diffusion resistors are formed on a diaphragm made of, for example, single-crystal silicon, and the diffusion resistors are bridge-connected. It is adhered by. The pedestal 10 is adhered to the bottom surface of the fixing portion 4 with a silicone resin or the like.
[0017]
The sensor case 3 is formed of a heat-resistant resin, for example, PPS is used. The lead frame 7 is electrically connected to a connector pin 11 connected to an external processing circuit (not shown), and the periphery of the connection point is sealed with a potting material 12. A housing 13 made of, for example, PBT is attached to the sensor case 3 by an adhesive portion 14 shown by a broken line. The details of the bonding portion 14 will be described later. A pressure introducing hole 15 for transmitting pressure to the pressure receiving surface of the sensor element 5 is formed inside the housing 13, and an O-ring 16 is provided at a tip of the housing 13, and the O-ring 16 is provided through the O-ring 16. It can be attached to a predetermined location.
[0018]
In the above configuration, when pressure is applied in the direction of the arrow shown in FIG. 1, the pressure is transmitted to the pressure receiving surface of the sensor element 5 in the sensor case 3 through the pressure introduction hole 15 of the housing 13. Then, the diaphragm of the sensor element 5 is deformed according to the pressure. The resistance change value of the diffusion resistor (not shown) corresponding to the deformation is taken out as a voltage from the bridge circuit, amplified by the signal processing IC 6, and output to an external processing circuit (not shown) via the lead frame 7 and the connector pins 11.
[0019]
Next, the bonding portion 14 between the sensor case 3 having the bonding structure of the present embodiment and the housing 13 will be described with reference to FIG.
[0020]
FIG. 2A is an enlarged cross-sectional view around the bonding portion 14 in FIG. An annular concave portion 17 is formed in the sensor case 3 as the adhesive portion 14, and an annular convex portion 18 housed in the concave portion 17 of the sensor case 3 is formed in the housing 13 as the adhesive portion 14. In this example, the concave portion 17 is formed on the sensor case 3 side and the convex portion 18 is formed on the housing side. However, a convex portion may be formed on the sensor case 3 side and a concave portion may be formed on the housing side.
[0021]
When the protrusion 18 of the housing 13 is inserted into the recess 17 of the sensor case 3 and the protrusion tip of the protrusion 18 contacts the bottom surface of the recess 17, the inner and outer circumferences are located between the side surfaces of the protrusion 18 and the recess 17. A predetermined gap 19 is provided for each. By filling the gap 19 with an adhesive 20 made of, for example, a hard epoxy resin, the adhesive 20 and the inner and outer peripheral sides of the concave portion 17 of the sensor case 3, and the adhesive 20 and the convex portion 18 of the housing 13 are formed. The inner and outer peripheral sides are adhered.
[0022]
Here, for the heat resistance of wire bonding, for example, PPS which is a resin having excellent heat resistance is used as the sensor case 3, a hard epoxy resin is used as the adhesive 20, and the housing 13 is slightly heat resistant than PPS. Inferior but inexpensive PBT is used. The linear expansion coefficient of each resin material is about 28 ppm for PPS, about 39 ppm for hard epoxy resin, and about 52 ppm for PBT.
[0023]
The inventors of the present invention have previously conducted a cooling / heating cycle based on a use environment temperature (for example, −40 ° C. to 120 ° C.) after being actually assembled as a product, in a case where the bonding surface with the adhesive 20 is all flat. A durability test was performed. As a result, as shown in FIG. 2A, the inner peripheral side surface of the concave portion 17 of the sensor case 3 is defined as an A surface, the outer peripheral side surface is defined as a D surface, the inner peripheral side surface of the convex portion 18 of the housing 13 is defined as a B surface, and the outer peripheral side surface. Is the C surface, first, peeling occurred between the outermost surface D surface and the adhesive 20, and then peeling continued to the inner circumferential surfaces B and A, resulting in a leak path. Therefore, the present inventors decided to provide the protrusion 21 on the side surface in order to improve the adhesive force between the side surface of the convex portion 18 and the concave portion 17 in the bonding portion 14 and the adhesive 20.
[0024]
In the present embodiment, as shown in FIG. 2A, an example is shown in which protrusions 21 are formed on both inner peripheral side surfaces A and B of the protrusion 18 and the recess 17. The protrusion 21 is formed by integral resin molding when the sensor case 3 or the housing 13 is formed. For example, the protrusion 21 is formed uniformly over the entire periphery of the side surface of the convex portion 18 and the concave portion 17 formed in an annular shape. . However, it is not always necessary to form them uniformly over the entire circumference. For example, if the sensor case 3 and the housing 13 are within a range in which the space between the sensor case 3 and the housing 13 is hermetically sealed at the operating temperature, only a predetermined portion of the annular circumference or the height (in a direction orthogonal to the circumference) The projection 21 may be formed only in a predetermined portion of ()).
[0025]
Further, as shown in FIGS. 2B and 2C, the protrusion 21 is preferably formed in parallel with the direction in which the protrusion 18 is housed in the recess 17. This is because, when the projection 21 is formed simultaneously with the formation of the sensor case 3 or the housing 13 by integral resin molding, it is better to provide the gathers 21a in parallel to the direction in which the projections 18 are stored in the recesses 17 from the resin mold. This is because the direction in which the sensor case 3 and the housing 13 are pulled out substantially coincides with the direction in which the sensor case 3 and the housing 13 are pulled out, and it is easy to pull out.
[0026]
Further, the projection 21 has a plurality of gathers protruding in a streak shape having a predetermined height (for example, approximately 1/3 with respect to the distance between the A and B adhesive surfaces) and a width (for example, approximately equal to the height). 21a is even better. The gather 21a may have a wave shape having a predetermined height and interval as shown in FIG. 2B, or a rectangular shape having a predetermined height and interval as shown in FIG. 2C. May be. 2 (b) and 2 (c) are perspective views of the surface A having the protrusion 21 in the bonding portion 14 of FIG. 2 (a).
[0027]
Here, the adhesive force between the side surfaces of the convex portion 18 and the concave portion 17 and the adhesive 20 will be described. FIG. 3A is a diagram for explaining the adhesive force between the A surface of the sensor case 3 and the adhesive 20 when the projection 21 is not provided, and FIG. FIG. 6 is a diagram for explaining an adhesive force when a wavy gather 21a is provided on the A side in FIG.
[0028]
As shown in FIG. 3 (a), when the protrusion 21 is not provided on the surface A, the stress for peeling the adhesive 20 from the surface A in the direction of the white arrow (perpendicular to the surface A). Is applied, an adhesive force acts only between the adhesive 20 and the surface A of the sensor case 3 in a direction indicated by a broken-line arrow (a direction perpendicular to the surface A, that is, in a direction opposite to the applied stress). Resist.
[0029]
However, as shown in FIG. 3B, when the wavy gathers 21a, which are the projections 21, are provided on the A-side, the adhesive 20 and the A-side of the sensor case 3 have a larger surface area of the projected gathers 21a. The bonding area increases, and the bonding strength increases. Further, as in FIG. 3A, when a stress is applied to peel the adhesive 20 from the surface A in the direction of the white arrow, the gathers 21a as the protrusions 21 are applied as in FIG. The adhesive force acts in a direction (perpendicular to the A-plane) with respect to the stress applied to the point of action, and also in a shear direction perpendicular to the direction (normal direction to the point of action of the adhesive force). Strong adhesion works. Therefore, the provision of the protrusion 21 significantly increases the adhesive force between the adhesive 20 and the adhesive 20. In particular, the rectangular shape in FIG. 2C is more preferable than the wave shape in FIG. 2B because the adhesive force in the shear direction increases.
[0030]
As described above, by forming the gathers 21a, which are the projections 21, on both the inner peripheral side surfaces A and B, the adhesive force between the adhesive agent 20 and the A and B both side surfaces can be improved. Here, in the present embodiment, the protrusions 21 are not formed on both the outer peripheral side surfaces C and D and are kept flat. For example, when the protrusions 21 are provided on all the side surfaces A, B, C, and D, the individual adhesive strength between each surface and the adhesive 20 is improved. However, there is no place for stress to escape when stress is generated in the entire bonding portion 14 due to heat or the like, and peeling may occur between any surface and the adhesive 20, which may result in a leak path. Therefore, from the result of the case where the protrusion 21 is not provided, the protrusion 21 is not provided on the outer peripheral side surfaces C and D including the surface D where the peeling occurred first, and only the inner peripheral side surfaces A and B are provided. The projection 21 was provided. Thereby, the inner peripheral side surfaces A and B opposed to each other are firmly adhered to each other by the protruding portions 21, whereby the airtightness between the sensor case 3 and the housing 13 can be maintained. In addition, the outer peripheral side surfaces C and D, which are opposed to each other, do not form the protruding portion 21 and intentionally lower the adhesive force from the inner peripheral side surface side, so that the stress generated in the adhesive portion 14 is applied to the outer peripheral side surface side. Can be relaxed.
[0031]
As described above, the bonding structure of the present embodiment provides a more airtight bonding between the sensor case 3 and the housing 13 by providing the projection 21 having a predetermined shape on the bonding surface with the adhesive 20. Can be. If the protrusion 21 is formed on one of the inner and outer peripheral sides and the other side is flat, the sensor case 3 and the housing 13 can be more airtightly bonded to each other. Protrusions 21 may be formed on both side surfaces of the convex portion 18 and the concave portion 17 forming the side surface, and both side surfaces of the convex portion 18 and the concave portion 17 forming the inner peripheral side surface may be flat.
[0032]
In the present embodiment, as shown in FIGS. 2A to 2C, an example is shown in which the gathers 21a, which are a plurality of streak-like projections, are provided in the joining direction of the convex portions 18 and the concave portions 17. The present invention can be applied to any other protrusions 21 provided on the side surfaces of the convex portion 18 and the concave portion 17 of the bonding portion 14. For example, as shown in FIGS. 4A and 4B, the protrusion 21 may be formed in a direction substantially perpendicular to the direction in which the protrusion 18 of the bonding portion 14 is stored in the recess 17. Also, the protrusion 21 is not the shape of the gather 21a shown in FIGS. 2A to 2C and FIGS. 4A and 4B, but a plurality of protrusions as shown in FIG. 21b. Also in this case, the adhesive force between the adhesive 20 and the adhesive 20 can be increased by increasing the surface area of the projection 21b, and the adhesive force between the sensor case 3 or the housing 13 and the adhesive 20 can be increased by increasing the adhesive force in the shearing direction. Can be improved in adhesive strength. FIG. 4A is an enlarged view of the bonding portion 14 shown in FIG. 1 and shows an example in which the protrusion 21 is provided in a direction substantially perpendicular to the direction in which the protrusion 18 is stored in the recess 17. 4B is a perspective view of the A surface having the protrusion 21 in the bonding portion 14 of FIG. 4A, and FIG. 4C is a perspective view of the case where the protrusion 21b is provided on the A surface.
[0033]
Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be implemented with various modifications.
[0034]
In the present embodiment, as shown in FIGS. 2A and 4A, an example is shown in which the protrusions 21 are formed on both the inner peripheral side surfaces A and B. It may be formed on only one of the two surfaces. If the protrusion 21 is formed on at least one side, the adhesive force between the side and the adhesive 20 is improved. Furthermore, if the projections 21 are formed on at least one of the A, B, C, and D surfaces, it goes without saying that the adhesive strength of the entire adhesive portion 14 is improved.
[0035]
Further, in the present embodiment, as shown in FIG. 2A, both A and B surfaces on the inner peripheral side have protrusions 21 and both C and D surfaces on the outer peripheral side do not have protrusions. Although the example in which the inner and outer peripheral side surfaces are bonded to the adhesive 20 has been described, the purpose is not provided when the protrusions 21 are not formed on the inner peripheral side surfaces A and B or the outer peripheral side surfaces C and D. Since the stress is relaxed, it is not always necessary to fill the gap between A and B or between C and D with the adhesive 20.
[0036]
Further, in the present embodiment, the bonding structure between the sensor case 3 and the housing 13 in the pressure sensor device 1 is shown as an example of the bonding structure. 18 may be applied as long as it has a recess 17 on the other side and holds the sensor element inside.
[0037]
Further, in the present embodiment, an example has been described in which the material of the sensor case 3 and the material of the housing 13 are different from each other. However, the present invention can be applied to a case where the materials of the same composition are used.
[Brief description of the drawings]
FIG. 1 is a sectional view of a pressure sensor device according to the present embodiment.
FIGS. 2A and 2B are enlarged views of a bonding portion in FIG. 1A, in which FIG. 2A shows a case where a protrusion is provided along a bonding direction, and FIG. (A) is a perspective view in the case where a corrugated gather is provided, and (c) is a perspective view in the case where a rectangular gather is provided on the projection (A surface) of (a).
3A and 3B are cross-sectional views of the vicinity of an adhesive interface between an A surface of a sensor case and an adhesive. FIG. 3A shows a case where there is no protrusion, and FIG. 3B shows a case where a wavy gather is provided as a protrusion.
FIGS. 4A and 4B are enlarged views of a bonding portion in FIG. 1A, in which FIG. 4A shows a case where a protrusion is provided perpendicular to a bonding direction, and FIG. 4B is a diagram showing a protrusion of FIG. 7) is a perspective view when a rectangular gather is provided, and (c) is a perspective view when a protrusion is provided on the A surface of (a).
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Pressure sensor apparatus, 2 ... Sensor element, 3 ... Sensor case, 13 ... Housing, 14 ... Adhesion part, 17 ... Concave part, 18 ... Convex part, 20. ..Adhesive, 21 ... projections, 21a ... gathers, 21b ... projections

Claims (7)

An adhesive structure for airtightly bonding the sensor case and the housing that hold the sensor element therein,
One of the sensor case and the housing has an annular concave portion, and the other has an annular convex portion housed in the concave portion,
When the convex portion is housed in the concave portion, predetermined gaps are respectively formed between the inner and outer peripheral side surfaces of the convex portion and the inner and outer peripheral side surfaces of the concave portion,
Among the gaps, at least one of the inner gap and the outer gap is filled with an adhesive,
An adhesive structure comprising a protrusion having a predetermined shape on at least one of the side surfaces of the convex portion and the concave portion forming the gap filled with the adhesive. 2. The bonding structure according to claim 1, wherein the protrusion is provided on at least one side surface of the protrusion and the recess in one of the gaps on the inner peripheral side and the outer peripheral side. 3. The said protrusion part is provided in the both inner peripheral side surface of the said convex part and the said recessed part arrange | positioned facing, The both outer peripheral side surfaces of the said convex part and the said concave part are formed flat. Or the adhesive structure according to claim 2. The said protrusion part is provided in the both outer peripheral side of the said convex part and the said concave part arrange | positioned facing, The both inner peripheral side surfaces of the said convex part and the said concave part are formed flat. Or the adhesive structure according to claim 2. 5. The projection according to claim 1, wherein the projection is a plurality of gathers protruding in a streak shape having a predetermined height and width in parallel with a direction in which the projection is stored in the recess. An adhesive structure according to the item. The bonding structure according to any one of claims 1 to 5, wherein the protrusions are provided evenly around the entire side surface of the protrusion and / or the recess. The bonding structure according to any one of claims 1 to 6, wherein the housing has a pressure introduction hole, and the sensor element detects a pressure introduced from the pressure introduction hole.

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